POWDER TYPES & SUITABILITY
|CORROSION PROTECTION||Not recommended||Excellent|
|CHEMICAL RESISTANCE||Excellent||Very Good|
|APPLICATION PROPERTIES||Excellent||Very Good|
|+ Good Resistance||± Limited Resistance||– Poor Resistance|
|TYPES & SUITABILITY||EPOXY||EPOXY - POLYESTER||POLYESTER|
|Sulphuric Acid 10%||+||+||+|
|Sulphuric Acid. Conc.||-||-||-|
|Hydrochloric Acid 10%||+||+||+|
|Hydrochloric Acid. Conc.||±||±||±|
|Nitric Acid 10%||±||-||-|
|Nitric Acid. Conc.||-||-||-|
|Phosphoric Acid 50%||+||+||+|
|Caustic Soda 10%||+||±||+|
|Caustic Soda 30%||+||-||±|
|Acetic Acid 10%||+||+||+|
|Tartaric Acid 5%||+||+||+|
|EPOXY||EPOXY - POLYESTER||POLYESTER|
|Lactic Acid 10%||+||+||+|
|Ethyl Alchohol 96%||+||+||+|
|Mehyl ethyl ketone||±||-||-|
|Hydrogen Peroxide 3%||±||-||-|
These can physically get in between the powder and the object that is being coated causing the coating to not bond. Care must be taken to ensure that the object to be coated is properly cleaned.
Powder Coatings will not stick to oily, greasy or waxy surfaces. Feeling the surface to detect oils is not good enough as oils cannot always be detect in this way. High pressure water cleaning and grit blasting do not guarantee to remove oils use of a degreasing chemical is usually the best solution.
Moisture can be a problem in both the form of water droplets and high humidity. Moisture can be both static and migrating. Care must be taken to ensure that the correct powder is used for this situation as many powders will fail to stick to damp surfaces and where moisture migrates water filled blisters can often be generated.
HEALTH & SAFETY INFORMATION
There are many reasons why coatings fail and this can normally be attributed to poor application and inept quality assurance practices. Below are a list of why the powder coating process might fail.
Ultra Violet radiation from the Sun will breakdown many coatings. Coatings may discolour, get brittle and crack.
These can be underneath the powder at coating time and can cause corrosion to the object leading to early failure of the coating. This endorses the need for a good working environment with rigid procedures.
A single layer of coating runs the risk of pinhole size coating failures. These permit chemicals to attack the unprotected surface and the bonding. Again, this puts the focus on quality assurance and procedures.
Some coatings are more brittle than other, overly brittle coatings my crack or chip.
Different type of coating handles abrasion and wear to differing extents. It is important to select the correct kind of coating to take account of wear and tea.